Projection Optical System with Single Aspheric Mirror
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Solution Overview
Problem
Existing projection optical systems face challenges with chromatic aberrations and require high assembly accuracy and manufacturing costs due to the use of multiple aspheric mirrors, especially in compact designs with oblique projection, which complicates the achievement of high imaging performance.
Innovation Solution
A compact projection optical system with a first imaging system comprising multiple lens elements and a second imaging system using a single concave aspheric mirror, arranged to minimize assembly complexity and costs, while maintaining high optical performance by satisfying specific conditions for angle and Abbe number ranges, and folding the optical path to achieve compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple aspheric mirrors are used to correct chromatic aberration and improve imaging performance, then optical performance is improved, but assembly accuracy requirements increase and manufacturing costs become high
Solution Approach 1:
The patent extracts the chromatic aberration correction function from the multiple mirror system and implements it through a single mirror with specific curvature characteristics. By taking out the essential function (chromatic aberration correction) and implementing it through a simplified structure (one mirror instead of three), the patent reduces assembly complexity while maintaining optical performance.
Solution Approach 2:
Instead of using multiple mirrors with complex aspheric surfaces to correct aberrations, the patent inverts the approach by using a single mirror with specifically designed curvature characteristics that inherently correct chromatic aberration. This inversion simplifies the system from multiple complex components to one optimized component.
2Reliability
If multiple aspheric mirrors are used to compensate for distortion in oblique projection systems, then imaging performance is improved, but manufacturing costs become high
Solution Approach 1:
The patent extracts the distortion compensation function from the multiple mirror system and implements it through a single mirror with optimized curvature. By separating the essential function (distortion compensation) from the complex multi-mirror structure, the patent achieves the same performance at lower manufacturing cost.
Solution Approach 2:
The patent replaces expensive, complex multi-mirror aspheric systems with a simpler, more cost-effective single mirror design. While the single mirror requires precise curvature control, it eliminates the need for multiple high-precision aspheric mirrors, thereby reducing overall manufacturing cost.
3Object-generated harmful factors
If a single mirror is used to eliminate chromatic aberration, then chromatic aberration is eliminated, but the system does not achieve compactness
Solution Approach 1:
The patent employs a mirror with specifically designed curvature characteristics (spherical or aspheric) that enables chromatic aberration correction while allowing for a compact optical path layout. The curved surface geometry is optimized to achieve both optical performance and compact form factor.
Solution Approach 2:
The patent uses the curvature dimension of the mirror surface to achieve dual functionality: chromatic aberration correction and compactness. By optimizing the mirror's curvature characteristics, the system achieves aberration correction without requiring a large physical footprint, effectively using the curvature dimension to solve both problems simultaneously.
4Volume of moving object
If oblique projection is used to achieve compactness, then device size is reduced, but imaging performance deteriorates due to trapezoidal distortion
Solution Approach 1:
The patent applies preliminary anti-action by designing the mirror curvature to pre-compensate for the trapezoidal distortion that will occur during oblique projection. The mirror's specific curvature characteristics are calculated in advance to counteract the expected distortion, thereby maintaining imaging performance even in the compact oblique projection configuration.
Solution Approach 2:
The patent changes the curvature parameters of the mirror to optimize performance for oblique projection. By adjusting the mirror's curvature characteristics (radius of curvature, aspheric coefficients), the system achieves both compactness and acceptable imaging performance, effectively using parameter optimization to resolve the contradiction between size and performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves reduced distortion and chromatic aberration correction with simplified assembly and lower manufacturing costs, enabling a high-performance, compact projection display device.
Implementation Method 1
a second imaging system using a single concave aspheric mirror
Implementation Method 2
a first imaging system comprising multiple lens elements
Data Source
AI summary
A projection optical system having a magnification side and a reduction side for forming a magnified image on a magnification side image surface conjugate with a reduction side conjugate image surface includes, arranged in order from the reduction side, a first imaging system including a plurality of lens elements and lens components and a second imaging system including a mirror having a concave, aspheric reflecting surface. An intermediate image is formed between the first imaging system and the second imaging system. The projection optical system satisfies specified conditions related to the travel of principal rays through the projection optical system and related to the Abbe number of a lens element having positive refractive power of the first imaging system. A projection display device includes the projection optical system and may include a light valve for modulating a light beam for projection on a screen.